644466804 has 24 divisors (see below), whose sum is σ = 1592212608. Its totient is φ = 202185600.

The previous prime is 644466799. The next prime is 644466811. The reversal of 644466804 is 408664446.

It is a happy number.

It is a super-2 number, since 2×644466804² = 830674922915948832, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1579372 + ... + 1579779.

It is an arithmetic number, because the mean of its divisors is an integer number (66342192).

Almost surely, 2^644466804 is an apocalyptic number.

It is an amenable number.

644466804 is an abundant number, since it is smaller than the sum of its proper divisors (947745804).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644466804 is a wasteful number, since it uses less digits than its factorization.

644466804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3159175 (or 3159173 counting only the distinct ones).

The product of its (nonzero) digits is 442368, while the sum is 42.

The square root of 644466804 is about 25386.3507420819. The cubic root of 644466804 is about 863.7741125446.

The spelling of 644466804 in words is "six hundred forty-four million, four hundred sixty-six thousand, eight hundred four".